Portal hypertension
Overview
In medicine, portal hypertension is hypertension (high blood pressure) in the portal vein and its tributaries. It is often defined as a portal pressure gradient (the difference in pressure between the portal vein and the hepatic veins) of 5 mm Hg or greater.
Symptoms
Consequences of portal hypertension are caused by blood being forced down alternate channels by the increased resistance to flow through the portal system. They include: * Ascites (free fluid in the peritoneal cavity) * Hepatic encephalopathy * Increased risk of spontaneous bacterial peritonitis * Increased risk of hepatorenal syndrome * Splenomegaly (enlargement of the spleen) with consequent sequestration therein of red blood cells, white blood cells, and platelets, together leading to mild pancytopenia * Portacaval anastomoses (esophageal varices, hemorrhoids, caput medusae), with esophageal varices posing an ongoing risk of life-threatening hemorrhage, with haematemesis or malaena.
Causes
Many conditions can result in portal hypertension. In North America and Europe, it is usually the result of cirrhosis of the liver, but can also resut from alcoholic hepatitis, idiopathic non-cirrhotic portal hypertension, congenital hepatic fibrosis, partial nodular transformation, Budd-Chiari syndrome, portal vein thrombosis and rarely, right heart failure However, in less industrialized parts of the world, climate permitting, the major cause is schistosomiasis.
Treatment
Treatment with a non-selective beta blocker is often commenced once portal hypertension has been diagnosed, and almost always if there has already been bleeding from esophageal varices. Typically, this is done with either propranolol or nadolol. The addition of a nitrate, such as isosorbide mononitrate, to the beta blocker is more effective than using beta blockers alone and may be the preferred regimen in those people with portal hypertension who have already experienced variceal bleeding. In acute or severe complications of the hypertension, such as bleeding varices, intravenous octreotide (a somatostatin analogue) or intravenous terlipressin (an antidiuretic hormone analogue) is commenced to decrease the portal pressure.